<!DOCTYPE html>
<html xmlns:th="http://www.thymeleaf.org">
    <head>
        <meta charset="UTF-8">
        <title>if</title>
    </head>
    <body>
        <h3>if/unless</h3>
        <p th:if="${flag}" th:text="|welcome to my application,${flag}|"></p>
        <br>
        <p th:unless="${!flag}" th:text="'welcome to my application,' + ${flag}"></p>
    </body>
</html>